The general problem addressed by this invention is how to identify the different multipath components in a received WCDMA signal. This function is typically handled by a block in the receiver called the Multipath Searcher.
The characteristics of a dynamic fading channel are that it will degrade the performance of a multipath searcher using long coherent integration times. Another problem resulting from the characteristics of quickly changing fading channels is that the results from the early portion of the search cannot be meaningfully compared to the results from the later portion of the search because the channel has changed significantly in the intervening time.
The conventional approach employs a bank of correlators in the searcher and then runs the searcher over the certain code space (searching window). In order to locate all possible paths, it is necessary to consider the worst case. The longer the searcher window is, the larger the bank of correlators. The control logic is very simple for this approach, but more hardware resources are needed.
Usually there are two stages in a multipath searcher. The first stage is to get the multipath profile as described above. That is, the first stage locates all of the energy peaks and stores the energy peaks in a profile. The second stage is to identify valid energy peaks from an available profile. Due to a harsh wireless environment, false energy peaks exist in the multipath searcher profile. These may cause the multipath searcher to find paths, which do not actually describe the received multipath, creating a “false alarm” result for the multipath searcher. The general problem addressed by the present invention is how to sort the multipath profile reliably and efficiently. It would be advantageous to reduce the possibility of “false alarms” and improve the receiver's performance.